Low-tension spark-plug.



G. L. TRUESDELL.

LOW TENSION SPARK PLUG. APPLICATION FILED SEPT.2I. 191s.

Patented Apr. 16, 1918.

invrrnn snares PATENT orrion.

GEORGE L. TRUESDELL, 0F REDWOOD FALLS, MINNESOTA.

LOW-TENSION SPARK-PLUG.

To all whom it may concern:

Be it known that I, GEORGE L. TRUEsDELL, a citizen of the United States, residing at Redwood Falls, in the county of Redwood, State of Minnesota, have invented certain new and useful Improvements in Low-Ten: sion Spark-Plugs; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the class of igniting devices for internal combustion engines, and has particular reference to a low tension spark plug.-

The primary object of the invention is to construct a spark plug which may be successfully employed upon any gas engine by employing a low tension current and one which will make use of a low tension current even though it is operated on an engine using a very high compression which ordinarily increases the resistance to the passage of the spark across the terminals of the plug of an ordinary make and break system. By providing a successful low tension spark plug, the ignition question in internal combustion engines is greatly simplified in that it makes it possible to use a low tension current which may vary more or less without destroying the efi'ectiveness of the spark, a condition which does not exist in other ignition circuits, since it is necessary in the latter to maintain the strength of the current up to a high degree. As a result, the cost of the operation of a low tension system is a fraction of that which is necessary to maintain a high tension system, since there are fewer parts in the system, and those which remain are of such a character that they seldom get out of order. The timing of the sparkis very easily accomplished and can be done while the engine is running, a further advantage rising from the low tension system which my in-' vention makes successful.

With the above object in View and such other objects relative to the construction of the spark plug which will hereinafter appear, my invention will now be fully set forth and described, reference being had to the accompanying drawings.

In the drawings,

Figure 1 is a vertical section,

Fig. 2 is a section on line 2-2 of Fig. 1,

Specification of Letters Patent. 7 Patented Apr, 16, 1918, Application filed. September 21, 1916. Serial No. 121,455.

Fig. 3 is a sectional detail; and

Fig. 4: is a further detail.

Referring more particularly to the drawings, 1 indicates a plug member which is preferably made of brass and is threaded to go into the usual plug opening in the head of a cylinder. The plug 1 is provided with a central vertical cavity 2 in the upper portion of the body, and terminates at its lower end in a vertical bore 3 which centrally. extends to the lower section-of the body. The

cavity 2 is threaded to receive a stem 1 of brass or other suitable metal or material, which is provided with a central bore 5 which forms a continuation of the bore 3,'the stem 4 terminating at its upper end in a Hat dishlike receptacle 6 having an upwardly extending annular wall 7. The annular wall 7 is provided with an internal shoulder 8 upon which seats the diaphragm 9 into which is threaded the iron shell 10. The shell 10 forms a housing for the electro-magnetic coil 11 which is wound around an iron core 12. The latter, is secured to the screw 13 which is passed centrally through the end wall of the casinglO, and is threaded into the core 12. The housing 6 is of sufiicient depth to permit a disk-shaped armature 1 1 to reciprocate vertically therein, under the influence of the electro-magnet 11, the armature 14 having a stem 15 which extends downwardly through the bores 5 and 3, and terminates at its lower end in a flat tongue 16. The tongue 16 is vertically slotted and receives through the slot a contact finger 17 which is formed of spring metal, and has one end secured to the lower end of the plug 1. The stem 15 is provided within the chamber 6 with a collar 18 which is rigidly mounted upon the stem and receives upon its upper face, the forked ends of a leaf spring 19 whose opposite end is riveted or otherwise secured to the bottom wall of the chamber 6. The spring 19 serves to normally hold the armature in its lowered position, so that the spring contact 17 does not lie against the lower end of the slot in the tongue 16. I

The plug 1 is provided at one side of the cavity 2 with a vertical bore 20 in which is fitted the insulated electrode, 21 which is held in position by means of the upper lock nut 22 and the lower lock nut 23. At its upper end the electrode member 21 is provided with into the contact point which is provided with a platinumtip and opposes the corresponding tipped end of the spring contact 17. The contact 17 and the contact 25 are in normal engagement, and the contact therebetween is broken by'ineans of the stem 15 when the armature 14 is elevated by the electro-magnet 11. spring contact 17 passes through a slot in the lower end of the stem 15, so that when the armature 1 4; is attracted, the contact 17 is not immediately. lifted, but the current through the contact is allowed to. build upto a certain degree before the break is made so that the spark will be of suitably heavy character to ignite the charge. The coil 11 is provided with anattachment plug 26 which is preferably entered through the top of the casing 10, and serves to connect the free end of the coil in the ignition system.

The operation of the plug is obvious from the foregoing description, but it should be, noted that thevarious steps of the operation,

of the plug are carried out in a manner which produces a heavy spark with a low engine of large size. Furthermore, this heavy spark will result in spite of the fact that the engine may be of the high compression type; The armature is of a construction which insuresthe positive opera- Copies of this patent may be obtained for five cents each, by a Washington, D, 0

As above stated, the

tion of the plug since it is of such area With respect to the power of the plug that its attraction is a strong one and the contacts 17 and 25 will be snapped apart with a violent break. The parts of'the plug are easily accessible and since they are few in number and without complication, the plug may be manufactured at a comparatively low cost, and may. furthermore be installed upon automobiles without disturbing to any great eX- tent the original wiring system,

What claim i r A l w te s on park. pl g, mp s in combination, a body, a casing surmounting the body. an electro-magnetic coil mounted in the casing and providing a chamber in its lowerend, a disk armature operative in said chamber, a stem extending downwardlyfrom the armature and, through said body, the lower end; of the stem having a vertically elongated loop formed thereon, a rigid conac a ds r i ie t- Qnt c n norma ng g ment with the rigid contact, said resilient onta t x ending thr ugh a d oopl and normally out of contact therewith, but within the range of. the movement oi the lower 19 at 9= 911 Q tha upon the upwar stroke oi the stem the resilient contact will be separated, from the rigid contact at the nd.- f h t qk f th ar ature n t m nr whet f, l ffiX- my ig re,

n he presene Qt t o w t e se EOR E aT UE DE L- Witnesses :v

H- W- WA P; Manet.-

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